#semiconductor fab

Today's technology in the spotlight is: minifab, an incomplete version of which is known as "minimal fab".

Silicon carbide (SiC) is rapidly emerging as a game-changing material in the semiconductor industry. Its superior performance in high-power applications — such as electric vehicles, power grids, and renewable energy — sets it apart from traditional silicon-based solutions. With a wide bandgap, high electron mobility, and excellent thermal conductivity, SiC enables more efficient power devices, reducing energy loss and enhancing performance.

This article explores SiC crystal growth and wafer processing techniques, shedding light on the challenges and innovations driving the scalability and cost-effectiveness of SiC semiconductor manufacturing.

1. Fundamentals of SiC Crystal Growth and Material Properties

1.1 SiC Requirements

SiC is integral to modern power applications due to its exceptional properties, including a bandgap three times wider than silicon and a significantly higher critical electric field. These characteristics enable SiC-based power devices to operate at higher voltages and temperatures while reducing power losses and heat dissipation requirements.

Orbit & Skyline Semiconductor Fab Services specializes in precision processing and advanced fabrication solutions tailored for SiC technology, ensuring high-performance outcomes for semiconductor manufacturers.

1.2 SiC Crystal Structure

Silicon carbide exists in over 250 polytypes, each with unique electrical properties. Among them, 4H-SiC is the most favored due to its high electron mobility, breakdown voltage, and thermal conductivity. However, growing SiC crystals at industrial scales presents significant challenges, primarily due to the high processing temperatures (exceeding 2000°C) and the slow growth rates required to maintain quality and minimize defects.

1.3 SiC Boule Growth Methods

The semiconductor industry primarily employs three major methods for growing SiC boules, with the Physical Vapor Transport (PVT) method being the most prevalent. PVT relies on sublimation due to the lack of a stable liquid phase for SiC. Despite its advantages, challenges such as micropipes, stacking faults, and dislocation densities persist.

Orbit & Skyline’s process engineering team optimizes growth techniques to maximize yield and reduce defects, ensuring superior wafer quality. By fine-tuning parameters such as temperature control and pressure regulation, we enhance SiC crystal production efficiency.

1.4 Physical Vapor Transport (PVT) Process

The PVT process involves melting high purity SiC powder in a growth chamber at temperatures exceeding 2000°C. The sublimated vapor then deposits onto a seed crystal, gradually forming a high-quality SiC boule. This method enables precise control over doping levels, essential for tailoring electrical characteristics. N-type doping (typically using nitrogen) enhances conductivity, while p-type doping (using aluminium) influences the polytype formation, affecting overall device performance.

2. From Boule to Epi-Ready Wafer

2.1 SiC Hardness and Processing Challenges

SiC is one of the hardest materials known, ranking 9–9.5 on the Mohs scale. This extreme hardness complicates the slicing and processing of SiC boules into wafers. Specialized grinding, lapping, and polishing techniques are required to achieve the precise dimensions necessary for semiconductor applications.

Orbit & Skyline’s Equipment Engineering services provide tailored solutions to overcome these challenges, ensuring precise wafer preparation for further processing.

2.2 Wafer Slicing and Surface Preparation

SiC boules undergo slicing using multi-wire saws coated with diamond slurry. This process must balance kerf loss (material waste) and throughput efficiency. Following slicing, wafers undergo lapping to ensure uniform thickness and surface quality, crucial for subsequent epitaxial growth.

2.3 Epi-Ready Polishing and Surface Finishing

To achieve EPI-ready surfaces, wafers undergo Chemical Mechanical Polishing (CMP), combining mechanical abrasion with chemical etching. Innovations in CMP technology, such as rapid thinning techniques, enhance material removal rates while maintaining surface integrity. This ensures defect-free epitaxial layers, which are critical for high-performance semiconductor applications.

3. Epitaxial Growth and Doping of SiC

3.1 High-Temperature Chemical Vapor Deposition (HT-CVD)

Epitaxial growth involves depositing thin, defect-free SiC layers on wafers to enhance electrical performance. HT-CVD is the industry standard, offering precise control over doping concentration and layer thickness. By using silicon and carbon precursors, diluted in hydrogen or argon carrier gases, HT-CVD facilitates uniform SiC layer growth.

3.2 Alternative Epitaxy Methods

Other epitaxy methods, such as Molecular Beam Epitaxy (MBE) and Liquid Phase Epitaxy (LPE), have been explored. However, challenges in impurity control, growth rate limitations, and scalability make HT-CVD the preferred approach for large-scale SiC production.

3.3 Scaling to 8” and 200mm Wafers

With the industry shifting towards 8” (200mm) SiC wafers, significant improvements in slicing and polishing processes have been made. Advanced wafer thinning and surface finishing techniques ensure high yield and minimal defect rates. The transition to larger wafers increases device yield per wafer while optimizing fabrication costs.

Conclusion

SiC wafer technology continues to evolve, with advances in boule growth, wafer slicing, and epitaxial deposition driving the transition from 6” to 8” wafers. The industry’s focus on improving material quality and reducing processing costs ensures that SiC remains a competitive alternative to silicon in high-power applications.

Orbit & Skyline brings 15+ years of expertise, and a global team of 500+ engineers dedicated to advancing semiconductor technologies. As a trusted partner in the industry, we provide innovative solutions for SiC processing, fabrication, and equipment engineering.

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